There is too big gap between these 76mm guns (66, 67 or 68 penetration) and for example 76mm F-34 gun (86 penetration), but I don't suggest to improve these guns AP penetration too much as these guns are used on tier 4 tanks.

Main reason these guns have (had) poor performance, was due to low velocity and poor ammunition quality (low nose hardness). But as Wargaming has distanced World of Tanks far away from anything remotely resembling historical accuracy, that hardly can be considered a proper argument these days.

However, why should everything be the same across nations? Why should these guns have the same penetration as those in other nations? Can't we have some variation? Besides, what would an increase from 66 mm to 70 mm actually accomplish? Would it open up armor sections otherwise impenetrable?

Main reason these guns have (had) poor performance, was due to low velocity and poor ammunition quality (low nose hardness). But as Wargaming has distanced World of Tanks far away from anything remotely resembling historical accuracy, that hardly can be considered a proper argument these days.

However, why should everything be the same across nations? Why should these guns have the same penetration as those in other nations? Can't we have some variation? Besides, what would an increase from 66 mm to 70 mm actually accomplish? Would it open up armor sections otherwise impenetrable?

on WoT Blitz I got A-32 with equipment which increases penetration from 66mm -> 69mm and even after that you can notice some differences against heavier armored enemies (ofc it won't dramatically boost success rate, still many bounces but better than default 66mm)

ofc on WoT PC you have an option to use HE ammo type, more likely than on WoT Blitz (38 vs 20 penetration )

on WoT Blitz I got A-32 with equipment which increases penetration from 66mm -> 69mm and even after that you can notice some differences against heavier armored enemies (ofc it won't dramatically boost success rate, still many bounces but better than default 66mm)

ofc on WoT PC you have an option to use HE ammo type, more likely than on WoT Blitz (38 vs 20 penetration )